1. Field of the Invention
The present invention relates to an organic light emitting diode (OLED) display device and a method of manufacturing the same, and more particularly, to an active OLED display device and a method of manufacturing the same.
2. Discussion of the Related Art
With the advance of information communication technology, the demand for information display devices is rapidly increasing, and thus, the research and development of information display devices are being actively done. As the research and development of information display devices accelerate, display devices tend to realize a large screen, high resolution, a thin thickness, high definition, and a light weight.
Today is the mobile age, and, as a representative type of information display device which has noticeable advantages in thinning and lightening, flat panel display devices include liquid crystal display (LCD) devices, OLED display devices, etc.
Among such flat panel display devices, the OLED display devices have low power consumption, a good contrast ratio, a wide viewing angle, and a fast response time, and thus are attracting much attention as next generation flat panel display devices, following LCD devices. Also, recently, as research on enlargement is intensively done, technology for enhancing luminance uniformity and luminance is advancing.
In the technology for enhancing luminance, there is a micro-cavity. The micro-cavity denotes a state or structure in which light is repeatedly reflected in a certain section, and amplified by constructive interference. To apply the micro-cavity structure, a plurality of reflective electrodes which have different step heights for each pixel may be respectively formed in a plurality of anode electrodes.
FIG. 1 is a sectional view illustrating a portion of a related art OLED display device.
As illustrated in FIG. 1, the related art OLED display device includes a substrate 101, a thin film transistor TR, a passivation layer 110, a planarizing layer 120, a reflective electrode 130, and an anode electrode 140.
The thin film transistor TR is formed in each of a plurality of pixels P that are defined in the substrate 101, and the passivation layer 110 and the planarizing layer 120 are formed on the thin film transistor TR. The anode electrode 140 is formed on the planarizing layer 120, and the reflective electrode 130 is formed under the anode electrode 140. Although not shown, the reflective electrode 130 may be formed under the anode electrode 140, and the anode electrode 140 may include the reflective electrode 130.
The reflective electrode 130 includes a reflective layer 131. Between the reflective layer 131 and cathode electrodes (not shown), light emitted from an organic emitting layer (not shown) is repeatedly reflected, amplified by constructive inference, and emitted to the outside. In this case, the pixels P emit light of different wavelengths, and thus, a distance corresponding to an integer multiple of a half wavelength of the light emitted from each pixel P should be set as a distance over which the light is repeatedly reflected, for causing constructive interference. That is, a distance between the reflective layer 131 and the cathode electrode should match the distance corresponding to the integer multiple of the half wavelength of the light emitted from each pixel P. The distance between the reflective layer 131 and the cathode electrode is called an optical distance of the micro-cavity.
In order to set a plurality of the optical distances for each pixel P differently, the reflective electrode 130 may include a transparent layer 132. FIG. 1 illustrates an example in which the transparent layer 132 is formed in only the rightmost pixel P. However, the transparent layer 312 may be formed on any one or more of the plurality of pixels P depending on light emitted from each pixel P. Also, in order to set the optical distance suitable for each pixel P, the transparent layer 132 may be formed on one or more of the pixels P illustrated in FIG. 1.
In this way, when the transparent layers 132 are uniquely formed for each respective pixel P, the number of mask processes increases, which further causes a reduction in process efficiency.